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Author: Subject: So what can I do with a liter of pyridine?
evil_lurker
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biggrin.gif posted on 23-6-2006 at 21:28
So what can I do with a liter of pyridine?


I found a supplier that actually sold me a liter of pyridine via the internet, no questions asked... :D

And to make it an even sweeter deal, it cost under $100, and was shipped ORM-D (no-hazmat fees, woo hoo!).

Supposedly its en-route and I'm looking forward to getting it so I can synthesize some bromobenzene... hopefully my door won't get kicked in before I can get that done! :P

So other than making bromobenzene, any other ideas on stuff I can make with this? (other than a big stink or non-working testicles)
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[*] posted on 24-6-2006 at 01:44


PCC (pyridinium chloro-chromate) for selective oxidation of alcohols to aldehydes? Requires CrO3 though.

[Edited on 24-6-2006 by Jome]




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[*] posted on 24-6-2006 at 02:45


Pyridine is one of those solvents that can be used for nonaqueos electrolysis.

It can be used as starting point for compounds that contain pyridine ring just like benzene can be used to make complex aromatic compounds.

A. Brenthsen - A Textbook of Organic Chemistry, London 1941, page 680
Quote:

Pyridine, C6H5N, resembles benzene in many points:
1. It is even more stable than benzene, and yields substituted derivatives with sulphuric and nitric acids or the halogens, but not so readily as benzene. Sulphonic acids are obtained at very high temperatures only, and only a few chloro- and bromo-pyridines have been prepared. Pyridine and its carboxylic acids are not affected by oxidizing agents.
2. Its derivatives resemble those of benzene. Thus its homologues (and also quinoline, &c.) are transformed into pyridine carboxylic acids when oxidised, and these acids yield pyridine when distilled with lime, just as benzoic acid yields benzene.
3. The isomeric relations are also precisely analogous to those of the benzene derivatives. Thus the number of the isomeric mono-derivatives of pyridine is the same as that of the isomeric bi-derivatives of benzene, viz. three; and the number of the bi-derivatives of pyridine, containing the same substituents, the same as that of the benzene derivatives, C6H3X3, viz. six.
4. Just as two benzene nuclei can form naphthalene, so can a benzene and a pyridine form the compound quinoline.
5. The products of reduction are likewise analogous. Pyridine like benzene yields a hexahydro derivative, C5H11N, only somewhat more readily; this is known as piperidine. Quinoline yields a tetrahydro-derivative, C12H11N, which is analogous to anthracene dihydride. In these latter compounds further combination with hydrogen my take place, but there is likewise a tendency to the reproduction of the original bases.

page 681
Quote:

In contradiction to the neutral benzene hydrocarbons, pyridine and its homologues are bases of the same order of strength as aniline and have characteristic odours. Pyridine is readily soluble in water, but quinoline only slightly so. They distill or sublime without decomposiition, and form salts; those with hydrochloric and sulphuric acids are for the most part readily soluble, while those with chromic acid or hydroferrocyanic acids, though often characteristic, are usually only sparingly soluble; they also form double salts with chlorides of platinum, gold and mercury, most of which are sparingly soluble, e.g. (C5H5N)2H2PtCl6?.

The bases are tetriary, and hence cannot be acetylated; they combine however, with alkyl iodides, yielding quaternary ammonium salts, e.g. pyridine and methyl iodide yield [formula unreadable] methyl-pyridonium iodide.


Edit: Pyridine is quite toxic, so treat it with respect!

[Edited on 24-6-2006 by chromium]
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[*] posted on 24-6-2006 at 05:57


How are going to make bromobenzene from pyridine? I don't get that.

Pyridine can be used as solvent for room-temperature electrolysis of lithium salts to obtain the metal. I haven't tried that (I have a bit of pyridine, but no Lithium salts), but it supposedly works. Be aware that the anode products must be kept separate from the lithium, and that chlorine and bromine (from LiBr or LiCl) will react with the pyridine, forming halogenated derivatives and HCl or HBr. Only iodine doesn't react, and LiI should therefore be the preferred electrolyte.

Pyridine is a basic solvent (forms crystalline pyridinium salts with acids) and can be used for shifting the equilibrium to the product side in certain reactions which take place under evolution of a hydrogen halide or other acid.

Be aware that pyridine stinks, so use it outside or in a fume hood. You can't work with it indoors.

If you try the lithium electrolysis, please report it and make pics! I and a lot of other members would be highly interested.




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[*] posted on 25-6-2006 at 03:39


You could make a bit of original Karl-Fischer reagent for determination of water.
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[*] posted on 25-6-2006 at 10:36


You can make bromobenzene according to Vogel's III'rd using pyridine, bromine, and benzene.

The pyridine supposedly acts as a halogen carrier which allows the ring to be brominated.

By products are p-dibromobenzene which after primary distillation are crystalized out of the solution by putting into the freezer and filtering.

Re-distillation yields pure product.
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[*] posted on 25-6-2006 at 10:48


You don't need pyridine for making bromobenzene. That's a waste of pyridine.
Bromobenzene is made from benzene + bromine in the cold with a catalyst like FeBr3 (just add some iron powder, it reacts with the bromine). The evolution of HBr is the indication that the reaction has started. The benzene should be present in excess, and the mixture is separated by distillation afterwards.




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[*] posted on 25-6-2006 at 18:30


Quote:
Originally posted by garage chemist
You don't need pyridine for making bromobenzene. That's a waste of pyridine.
Bromobenzene is made from benzene + bromine in the cold with a catalyst like FeBr3 (just add some iron powder, it reacts with the bromine). The evolution of HBr is the indication that the reaction has started. The benzene should be present in excess, and the mixture is separated by distillation afterwards.


I seen it, but thought it best though to stick to the write up as provided. The reaction from what I have seen needs to be performed dry, and I wasn't too sure of my abiltity to create an anhydrous catalyst. Plus I didn't know how much catalyst to add to the reaction to keep it under control and moving at the proper rate.

Still though, 9ml of pyridine is all it takes per liter of benzene used. While it might be a waste of pyridine, at least it won't be very much.
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[*] posted on 27-6-2006 at 13:27


I have seen the use of pyridine for capture of H+ which is useful to promote some reactions, as noted by garage chemist.

I find it very interesting that pyridine can be used as a catalyst for the bromination of benzene. I can speculate that it functions as a carrier of Br+ at the N's lone pair site. Or perhaps the N carrys Br2 as "+Br:Br-". Anyone care to explain the actual mechanism?




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[*] posted on 28-6-2006 at 06:02


I can sell a few pyridine 1l analytical grade bottles for about 120$ + shipping if anyone is interested please PM me :)

[Edited on 28-6-2006 by Maja]
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